Wales head coach Warren Gatland says there are six places up for grabs in the final 31-man World Cup squad.
An experimental Wales side lost their first warm-up match 35-21 to Ireland in Cardiff on Saturday.
Gatland will cut the 46-man squad to "36 or 38" this week, before reducing it further on 31 August.
"We've probably got half a dozen places in our minds, we're not too sure about when we do finally select the squad," said Gatland.
"There are going to be some tough calls and we will see how training goes next week.
"Some players will need to have a pretty good look at their game."
Gatland selected an inexperienced team against Ireland that included four debutants in Ross Moriarty, Dominic Day, Tyler Morgan and Eli Walker.
The squad will travel to north Wales for another training camp this week and Gatland says the defeat by Ireland will have a bearing on his decision-making when he cuts the squad.
"This was an opportunity for a lot of players to go out there and perform so it will definitely have some relevance," he said.
|Jonathan Davies, former Wales fly-half|
|"For the Ireland boys this performance puts pressure on the first-choice players. We all know the Wales first-choice team, but they have not put them under any pressure, they have been poor today."|
"It was a bit hard for Tyler Morgan. He would have learnt a huge amount from that.
"You've go to put that down to experience. I remember Jonathan Davies came out here against Australia and he looked like a rabbit in the headlights.
"He got better from that and I'm sure Tyler will learn from that experience and Hallam Amos as well."
There was also a first cap for New Zealand born fly-half Gareth Anscombe, who replaced James Hook.
"I thought the two half-backs who came on did really well," added Gatland.
"Gareth Anscombe played nice and flat, taking the line."
Gatland confirmed that centre and stand-in captain Scott Williams was replaced as a precautionary measure to guard against a "tight calf".